Process of drawing metallic tubes.



No. 669,698. Patented Mar. l2, l90l. E. IVINS.

PROCESS OF DRAWING METALLIC TUBES.

(Application filed June 4, 1900.)

' (No Model.)

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Nrrnn ELLWOOD IVINS, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO FRANK A.WILMOT, OFBRIDGEPORT, CONNECTICUT.

PROCESS OF DRAWING METALLIC TUBES.

SPECIFICATION forming part Of Letters Patent No. 669,698, dated March12, 1901.

Application filed June ;,1900. b'erial No. 18,972. (No specimens.)

To all whom it may concern:

Be it known that I, ELLWOOD IVINS, a citizen of theUnited States,residing at Philadelphia, in the county of Philadelphia, State 5 ofPennsylvania, have invented new and useful Improvements in Processes ofDrawing Metallic Tubes, of which the following is a specification.

My invention relates to the cold-drawing of IO metallic tubes throughdies, and has for its object to cheapen and expedite the operation ofreducing or elongating the tube to the required finished dimensions,which object I accomplish by a process embracing a preliminary annealingand pickling of the tube, a

coating of the same designed to permit of any number of passes throughthe dies without any intermediate treatment whatsoever, the reduction ofthe tube by its passage through dies and over mandrels, and finally theremoval of the coating to restore the tube to its original condition.

In the accompanying drawings, Figure 1 is a sectional perspective Viewof a tube after the preliminary annealing and pickling. Fig. 2 is asimilar view of said tube coated. Fig. 3 is a similar view of said tubecoated and after it has been drawn. Fig. 4 is a similar view of saidtube drawn and with the coating removed, the same being in a finishedcondition.

To the above end the treatment preliminary todrawing consists in firstannealing the tube or hollow billet in the usual way, then dip- 5 pingthe same in an acid solution to clear or remove the oXid or scaleproduced by the annealing, then dipping it in water to remove all tracesof the acid solution, leaving it in the condition shown in Fig. l, andfinally 4o dipping it in a bath of molten soft metal,

preferably a mixture of tin and lead in suitable proportions, to coatthe tube both exteriorly and interiorly with said softer metal, as shownin Fig. 2. The tube so treated is 5 then drawn, preferably, over a fixedmandrel and'through a fixed die to obtain the required reduction orelongation, and this drawing is repeated, but without intermediateannealings and without any intermediate fresh coatings with the softmetal, over successivelysmaller mandrels and through successivelysmallerdies until the tube has attained the desired finished dimension, asshown in Fig.

3, it having been found that the coating of soft metal permits of thissuccessive drawing without intermediate annealings or intermediate freshcoatings with the soft metal, the same acting as a lubricant and notbecoming hardened to the density of the die and mandrel, as would be thecase with the surface of the tube itself were it exposed to the actionof the die and mandrel. After the drawing is finished the tube is thentreated, either chemically or mechanically, to remove the soft-metalinterior and exterior coating, thus leaving said tube in its originalcondition,with no trace of the soft-metal coating employed in theprocess of drawing the same, as shown in Fig. 4. A further valuableresult obtained is that any pittings that said tube may have acquiredduring the preliminary annealing and pickling are thoroughly obliteratedduring the drawing, leaving the tube when the soft-metal coating isremoved in a finished condition ready for use.

I am aware that it is not broadly new to coat a tube with soft. metal tofacilitate the passage thereof through a die, and such, therefore, I donot broadly claim; but I am not aware that tubes have been heretoforeannealed and pickled, coated with soft metal, then drawn throughsuccessively-smaller dies and over successively-smaller mandrels withoutintermediate aunealings or coatings, and finally treated to entirelyremove said soft metal, leaving the finished tube in its originalcondition.

Having thus described my invention, what I claim as new, and desire tosecure by Letters Patent, is-- The herein-described process of drawingand finishing tubes, consisting in first annealing the same, thenpickling the same, then coating the surfaces with antifriction metal,then drawing the same through suitable successivelysmaller dies withoutany intermediate annealing or pickling or fresh coating with soft metal,and finally removing the softmetal coating, substantially as set forth.

In testimony whereof I have hereunto set my hand in the presence of twosubscribing witnesses.

ELLWOOD IVINS.

Witnesses:

LYNNE K. LEWIS, ELIZABETH FRICK.

